Dataset consists of 4-day, 14-day, and full life responses of laboratory cultured mayflies (Neocloeon triangulifer) to nickel and zinc exposure. Responses were measured as mortality, body weight, development time, and reproduction. Water quality and analytical chemistry results associated with toxicity data are included. Additional data included are results of experiments assessing proportion of dissolved metal to nominal metal as influenced by the ratio of diatom diet dry mass present per volume of water.